MPPT sliding mode controller for PV system supplying a large scale interconnected grid

Abstract

This paper describes a PV system supplying a large scale interconnected grid. A PV array is connected to AC grid via a DC-DC boost converter and a three-phase three-level Voltage Source Converter (VSC). Maximum Power Point Tracking (MPPT) is implemented in the boost converter by means of a Simulink model using sliding mode controller by switching the duty cycle of the boost converter. A three phase VSC converts the 500 V DC link voltage to 260 V AC and keeps unity power factor. The VSC control system uses two control loops: an external control loop which regulates DC link voltage to 260 V AC and an internal control loop which regulates Id and Iq grid currents (active and reactive current components). Id current reference is the output of the DC voltage external controller. Iq current reference is set to zero in order to maintain unity power factor. Vd and Vq voltage outputs of the current controller are converted to three modulating signals used by the PWM Generator.